1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device and a method for manufacturing the same.
2. Discussion of the Related Art
Rapid development within the fields of information and communication has caused an increase in the demand for thin, lightweight and low cost display devices for viewing information. Industries that develop displays are responding to these needs by placing a high emphasis on developing flat panel type displays.
Historically, the Cathode Ray Tube (CRT) has been widely used as a display device in applications such as televisions, computer monitors, and the like, because CRT screens can display various colors having high luminance. However, the CRT cannot adequately satisfy present demands for display applications that require reduced volume and weight, portability, and low power consumption while having a large screen size and high resolution. Based on this need, the display industry has a placed high emphasis on developing flat panel displays to replace the CRT. Over the years, flat panel displays have been widely used in monitors for computers, spacecraft, and aircraft. Examples of flat panel display types currently used include the LCD, the electro luminescent display (ELD), the field emission display (FED), and the plasma display panel (PDP).
Characteristics required for an ideal flat panel display include a lightweight, high luminance, high efficiency, high resolution, high speed response time, low driving voltage, low power consumption, low cost, and natural color.
An LCD device having a thin and small size has been recently developed to sufficiently serve as a flat panel display device. Thus, demand for the LCD device is increasing.
Such an LCD device is based on the electric optical characteristic of a liquid crystal (LC) injected within a panel and the device does not emit light in unlike a plasma display panel (PDP) or a field emission display (FED). Accordingly, to view a picture displayed in an LCD panel, a separate light source, i.e., a back light assembly for uniformly irradiating light to a display panel of a picture is required.
Hereinafter, a related art LCD display and a method for manufacturing the same will be explained with reference to the accompanying drawings.
FIG. 1 is a plan view of a related art LCD device. Referring to FIG. 1, a gate line 11 is formed in one direction, and a data line 13 is formed to cross the gate line 11. A thin film transistor (TFT) 15 and a pixel electrode 17 are formed at a crossing point of the gate line 11 and the data line 13. The TFT 15 uses a part of the gate line 11 as a gate electrode 15a, and uses a part of the data line 13 as a source electrode 15b and a drain electrode 15c. A pixel electrode 17 is connected to the drain electrode 15c through a contact hole (not shown). Meanwhile, a storage capacitor 19 for maintaining a signal voltage applied to an LC is formed by overlapping the pixel electrode 17 with a part of an adjacent gate line 11a with a gate insulating film (not shown) interposed therebetween.
A related art LCD device will be explained in more detail with reference to FIG. 2.
FIG. 2 is a sectional view of a related art LCD device, taken along line I-I′ of FIG. 1.
As shown in FIG. 2, aluminum(Al), chromium(Cr), Molybdenum(Mo), and Al alloy are formed on a first substrate 1 by a sputtering method. Then, a gate line (not shown), a gate electrode 15a of a TFT, and a storage capacitor electrode 19a are formed with constant intervals by a photolithography process. Subsequently, a gate insulating film 21 consisting of SiOx or SiNx is formed on the first substrate 1 including the storage capacitor electrode 19a by Plasma Enhanced Chemical Vapor Deposition (PECVD). Then, a semiconductor layer 23 and an ohmic contact layer 23a used as channel layers of the TFT are layered on the gate insulating film 21 corresponding to an upper portion of the gate electrode 15a. 
Then, Al, Cr, Mo, and Al alloy are formed on the gate insulating film 21 including the semiconductor layer 23 and the ohmic contact layer 23a by a sputtering method, and patterned to form a data line and source electrode 15b and drain electrode 15c, and a metal layer 25 on the gate insulating film 21 corresponding to an upper portion of the storage capacitor electrode 19a. 
Subsequently, a passivation film 27 is formed on an entire surface including the source and drain electrodes 15b and 15c, and the metal layer 25. Then, a contact hole is formed to expose surfaces of the drain electrode 15c and the metal layer 25. A pixel electrode 17 electrically connected to the drain electrode 15c and the metal layer 25 through the contact hole is formed, thereby completing a method for manufacturing a TFT substrate.
Meanwhile, a color filter substrate opposed to the TFT substrate is formed by the following processes.
A color filter substrate consists of Red (R), green (G), and blue (B) color filter patterns 29 for displaying colors red, green, and blue, a black matrix 31 for dividing the respective color filter patterns 29 and shielding light, and a common electrode 33 for applying a voltage to an LC.
The black matrix 31 generally placed among the color filter patterns 29 is formed to shield a reverse tilted domain formed at a part where the pixel electrode 17 is not formed and around the pixel electrode 17.
Also, the black matrix 31 is formed to prevent leakage current of the TFT from being increased by shielding the irradiation of direct light to the TFT 15.
The black matrix 31 is formed of either a metal thin film such as Cr or a carbon based organic material. Also, the black matrix 31 may have a double layered-film structure of Cr/CrOx for low reflection.
After forming the black matrix 31, color filter patterns 29 for displaying colors are formed using a photo-process. At this time, the Red (R), green (G), and blue (B) color filter patterns 29 are generally formed by shifting one mask.
Subsequently, the common electrode 33 is formed for driving an LC with the pixel electrode 17 formed on the TFT substrate. The common electrode 33 is formed of Indium Tin Oxide (ITO) material from a of transparent electrode having excellent permeability, conductivity, and chemical and thermal stability by a sputtering method.
Meanwhile, although not shown, before forming the common electrode 33, an over coat layer may be formed of acryl based resin or polyimide based resin to protect and planarize the color filter patterns 29.
After the TFT substrate and the color filter substrate are manufactured as above, the two substrates are sealed and then an liquid crystal (LC) layer 100 is formed between the two substrates, thereby completing the related art LCD device.
However, the related art LCD device has the following problems.
A storage capacitor is formed by overlapping a gate line and a pixel electrode adjacent to each other. In the related art, since an overlapped area between the pixel electrode and the gate line is large, an aperture ratio is decreased.
To prevent decrease of the aperture ratio, there is a method for decreasing a width of a gate line. However, since a desired capacitance cannot be obtained in a case of decreasing the width of the gate line, there was a limit in decreasing the width of the gate line.